Combined SSCP/heteroduplex analysis in the screening for PAX6 mutations

We demonstrate the use of combined SSCP and heteroduplex analysis in the detection of PAX6 mutations using non-radioactive silver staining. A panel of aniridia patients was screened by this approach and we show that a greater number of mutations was detected than would have been found by running each technique alone. Six previously unreported aniridia mutations in PAX6 are also described..

A single-tube multiplex system for the simultaneous detection of 10 common cystic fibrosis mutations

We describe a nonisotopic single-tube polymerase chain reaction (PCR) multiplex system that detects 10 of the more common cystic fibrosis (CF) mutations (delta F508, delta I507, V520F, G551D, G542X, R553X, R117H, 621 + 1G-->T, N1303K, A455E). The use of this method detects approximately 90% of the CF alleles in the British population. Five exons of the CF gene are amplified simultaneously by PCR, followed by an overnight triple enzyme restriction digest, and then resolved by high-resolution gel acrylamide electrophoresis.

Antenatal screening for cystic fibrosis: a trial of the couple model

OBJECTIVE

To assess the delivery and acceptability of antenatal couple screening for cystic fibrosis. Carrier status was notified only when both members of a partnership had cystic fibrosis alleles and therefore a one in four risk of having an affected child.

DESIGN

Mouthwash samples were tested when both partners participated. Results were returned only to positive couples.

SETTING

Two large maternity hospitals in Edinburgh.

SUBJECTS

Screening was offered to all couples who booked at one of the two hospitals.

MAIN OUTCOME MEASURES

(a) The take up of screening, carriers and carrier couples identified, take up of prenatal diagnosis, and numbers of affected fetuses detected; (b) questionnaire measures of patient satisfaction and stress.

RESULTS

Screening was offered to 8536 couples. 714 (8.4%) were regarded as ineligible, usually because of late booking or absence of a partner. 1900 (24.3%) of the remainder declined screening. Among the 5922 screened couples, four tested positive--that is, both partners were cystic fibrosis heterozygotes. All four elected to have prenatal diagnosis. There were three terminations of pregnancy because of an affected fetus, one couple having two successive pregnancies with affected fetuses. The participation rate was 76% for eligible couples (5922/7822) and 69% for all couples (5922/8536). Only 89 screened couples (1.5%) requested information on individual carrier status. No anxiety was detected among a cohort of the screened population, and 99% of questioned participants expressed satisfaction with the concept of couple screening.

CONCLUSIONS

Antenatal couple screening is a satisfactory and acceptable way of screening for cystic fibrosis and has been adopted as routine in the two trial hospitals.

Use of stable dye-DNA intercalating complexes to detect cystic fibrosis mutations

Several dyes are now known which intercalate into double-stranded DNA with fluorescence enhancement. One such is TOTO (1,1'-(4,4,7,7-tetramethyl-4,7-diazaundecamethylene)-bis-4-[3-meth yl-2,3- dihydro-(benzo-1,3-thiazole)-2-methlyidene]-quinolinium tetraiodide), a homodimer of thiazole orange, whose complexes with DNA are stable to electrophoresis and show a 1000-fold enhancement after binding. We demonstrate that this reagent can be successfully used in combination with a laser-excited fluorescence gel scanner to detect the three most common cystic fibrosis mutant alleles, delta F508, G551D and G542X. This has potential application to mass population heterozygote screening.

Prenatal screening for cystic fibrosis: attitudes and responses of participants

A screening programme to detect cystic fibrosis heterozygotes has been running in the antenatal clinics of a major Edinburgh maternity hospital for more than 2 years. A questionnaire was used to assess participants' knowledge of the genetics of the disorder and their attitudes to being screened. The respondents were 64 female heterozygotes and 63 of their non-heterozygous male partners, 101 female controls and 100 male controls. Although the two groups of controls received far less direct information than the carriers and their partners, all four groups were well informed about the genetics of cystic fibrosis and the significance of being a gene carrier. A majority of each group felt that adequate information had been given in the information leaflet, that they understood the purpose of screening and that they were glad to have participated. There was a consensus that CF carrier testing should be routinely offered to pregnant women, and also that it should be available in family planning clinics and GP health centres, but not in schools.

A preliminary trial of couple screening for cystic fibrosis: designing an appropriate information leaflet

An information leaflet, inviting participation in an antenatal screening trial for cystic fibrosis, was sent to 388 couples together with the pregnant woman's first clinic appointment. The leaflet pointed out that couples would be treated as a unit and that further action would be taken only if both partners were found to carry mutant alleles. Participants and non-participants were also asked to fill in a questionnaire eliciting their views on the leaflet. Three hundred and twelve (80%) questionnaires were returned and 253 (65%) couples elected to be screened. More than 90% of respondents found the leaflet easy to understand, although about 10% wanted more information on cystic fibrosis. The main reason for entering the trial was to avoid the birth of an affected child, and the main reason for non-entry was opposition to termination of pregnancy. There was little anxiety about the prospect of being screened. However, more than a third of couples mis-identified their risk of both carrying a CF gene, despite the figure of 1 in 600 being explicitly stated in the leaflet.